Talc (derived frae Persie: تالک‎ tālk; Arabic: تلك‎ talk) is a meeneral componed o hydratedmagnesiumsilicate wi the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. In loose furm, it is the widely uised substance kent as talcum pouder. It occurs as foliatit tae fibrous masses, an in an exceptionally rare crystal furm. It haes a perfect basal cleavage, an the folia are non-elastic, awtho slichtly flexible. It is the saftest kent mineral an leetit as 1 on the Mohs hairdness scale. It can be easily scratched bi a fingernail. It is an aa sectile (can be cut wi a knife). It haes a speceefic gravity o 2.5–2.8, a clear or dusty luster, an is translucent tae opaque. Talc is nae soluble in watter, but it is slichtly soluble in dilute meeneral acids. Its colour ranges frae white tae gray or green an it haes a distinctly greasy feel. Its streak is white.